Add minimal handling of NEW_CONNECTION_ID frames

We actively use only the latest DCID received. And retire only
DCIDs requested by the peer to be retired.

Also changed the active_conn_id_limit to 2 as the minimum value allowed.

include/internal/quic_channel.h

@@ -207,6 +207,8 @@ void ossl_quic_channel_raise_protocol_error(QUIC_CHANNEL *ch,
 /* For RXDP use. */
 void ossl_quic_channel_on_remote_conn_close(QUIC_CHANNEL *ch,
  OSSL_QUIC_FRAME_CONN_CLOSE *f);
+void ossl_quic_channel_on_new_conn_id(QUIC_CHANNEL *ch,
+ OSSL_QUIC_FRAME_NEW_CONN_ID *f);
 
 /*
  * Queries and Accessors

ssl/quic/quic_channel.c

@@ -1174,7 +1174,7 @@ static int ch_generate_transport_params(QUIC_CHANNEL *ch)
  goto err;
 
  if (!ossl_quic_wire_encode_transport_param_int(&wpkt, QUIC_TPARAM_ACTIVE_CONN_ID_LIMIT,
- 4))
+ 2))
  goto err;
 
  if (!ossl_quic_wire_encode_transport_param_int(&wpkt, QUIC_TPARAM_INITIAL_MAX_DATA,
@@ -1206,16 +1206,17 @@ static int ch_generate_transport_params(QUIC_CHANNEL *ch)
  0))
  goto err;
 
+ if (!WPACKET_finish(&wpkt))
+ goto err;
+
+ wpkt_valid = 0;
+
  if (!WPACKET_get_total_written(&wpkt, &buf_len))
  goto err;
 
  ch->local_transport_params = (unsigned char *)buf_mem->data;
  buf_mem->data = NULL;
 
- if (!WPACKET_finish(&wpkt))
- goto err;
-
- wpkt_valid = 0;
 
  if (!ossl_quic_tls_set_transport_params(ch->qtls, ch->local_transport_params,
  buf_len))
@@ -1433,7 +1434,7 @@ static void ch_rx_handle_packet(QUIC_CHANNEL *ch)
 
  if (ossl_quic_pkt_type_is_encrypted(ch->qrx_pkt->hdr->type)) {
  if (!ch->have_received_enc_pkt) {
- ch->init_scid = ch->qrx_pkt->hdr->src_conn_id;
+ ch->cur_remote_dcid = ch->init_scid = ch->qrx_pkt->hdr->src_conn_id;
  ch->have_received_enc_pkt = 1;
 
  /*
@@ -2058,6 +2059,104 @@ void ossl_quic_channel_on_remote_conn_close(QUIC_CHANNEL *ch,
  ch_start_terminating(ch, &tcause, 0);
 }
 
+static void free_frame_data(unsigned char *buf, size_t buf_len, void *arg)
+{
+ OPENSSL_free(buf);
+}
+
+static int ch_enqueue_retire_conn_id(QUIC_CHANNEL *ch, uint64_t seq_num)
+{
+ BUF_MEM *buf_mem;
+ WPACKET wpkt;
+ size_t l;
+
+ if ((buf_mem = BUF_MEM_new()) == NULL)
+ return 0;
+
+ if (!WPACKET_init(&wpkt, buf_mem))
+ goto err;
+
+ if (!ossl_quic_wire_encode_frame_retire_conn_id(&wpkt, seq_num)) {
+ WPACKET_cleanup(&wpkt);
+ goto err;
+ }
+
+ WPACKET_finish(&wpkt);
+ if (!WPACKET_get_total_written(&wpkt, &l))
+ goto err;
+
+ if (ossl_quic_cfq_add_frame(ch->cfq, 1, QUIC_PN_SPACE_APP,
+ OSSL_QUIC_FRAME_TYPE_RETIRE_CONN_ID,
+ (unsigned char *)buf_mem->data, l,
+ free_frame_data, NULL) == NULL)
+ goto err;
+
+ buf_mem->data = NULL;
+ BUF_MEM_free(buf_mem);
+ return 1;
+
+err:
+ ossl_quic_channel_raise_protocol_error(ch,
+ QUIC_ERR_INTERNAL_ERROR,
+ OSSL_QUIC_FRAME_TYPE_NEW_CONN_ID,
+ "internal error enqueueing retire conn id");
+ BUF_MEM_free(buf_mem);
+ return 0;
+}
+
+void ossl_quic_channel_on_new_conn_id(QUIC_CHANNEL *ch,
+ OSSL_QUIC_FRAME_NEW_CONN_ID *f)
+{
+ uint64_t new_remote_seq_num = ch->cur_remote_seq_num;
+ uint64_t new_retire_prior_to = ch->cur_retire_prior_to;
+
+ if (!ossl_quic_channel_is_active(ch))
+ return;
+
+ /* We allow only two active connection ids; first check some constraints */
+
+ if (ch->cur_remote_dcid.id_len == 0) {
+ /* Changing from 0 length connection id is disallowed */
+ ossl_quic_channel_raise_protocol_error(ch,
+ QUIC_ERR_PROTOCOL_VIOLATION,
+ OSSL_QUIC_FRAME_TYPE_NEW_CONN_ID,
+ "zero length connection id in use");
+
+ return;
+ }
+
+ if (f->seq_num > new_remote_seq_num)
+ new_remote_seq_num = f->seq_num;
+ if (f->retire_prior_to > new_retire_prior_to)
+ new_retire_prior_to = f->retire_prior_to;
+
+ if (new_remote_seq_num - new_retire_prior_to > 1
+ /*
+ * RFC allows connection termination if we see 2 times the limit
+ * of conn ids to retire. We are a little bit more liberal.
+ */
+ || new_retire_prior_to - ch->cur_retire_prior_to > 10) {
+ /* Violation of our active conn id limit */
+ ossl_quic_channel_raise_protocol_error(ch,
+ QUIC_ERR_CONNECTION_ID_LIMIT_ERROR,
+ OSSL_QUIC_FRAME_TYPE_NEW_CONN_ID,
+ "active_connection_id limit violated");
+
+ return;
+ }
+
+ if (new_remote_seq_num > ch->cur_remote_seq_num) {
+ ch->cur_remote_seq_num = new_remote_seq_num;
+ ch->cur_remote_dcid = f->conn_id;
+ ossl_quic_tx_packetiser_set_cur_dcid(ch->txp, &ch->cur_remote_dcid);
+ }
+ while (new_retire_prior_to > ch->cur_retire_prior_to) {
+ if (!ch_enqueue_retire_conn_id(ch, ch->cur_retire_prior_to))
+ break;
+ ++ch->cur_retire_prior_to;
+ }
+}
+
 static void ch_raise_net_error(QUIC_CHANNEL *ch)
 {
  QUIC_TERMINATE_CAUSE tcause = {0};

ssl/quic/quic_channel_local.h

@@ -124,8 +124,10 @@ struct quic_channel_st {
  */
  QUIC_CONN_ID retry_scid;
 
- /* Server only: The DCID we currently use to talk to the peer. */
+ /* The DCID we currently use to talk to the peer and its sequence num. */
  QUIC_CONN_ID cur_remote_dcid;
+ uint64_t cur_remote_seq_num;
+ uint64_t cur_retire_prior_to;
  /* Server only: The DCID we currently expect the peer to use to talk to us. */
  QUIC_CONN_ID cur_local_dcid;
 

ssl/quic/quic_rx_depack.c

@@ -510,7 +510,7 @@ static int depack_do_frame_new_conn_id(PACKET *pkt,
  /* This frame makes the packet ACK eliciting */
  ackm_data->is_ack_eliciting = 1;
 
- /* TODO(QUIC): ADD CODE to send |frame_data.data| to the ch manager */
+ ossl_quic_channel_on_new_conn_id(ch, &frame_data);
 
  return 1;
 }
@@ -532,7 +532,7 @@ static int depack_do_frame_retire_conn_id(PACKET *pkt,
  /* This frame makes the packet ACK eliciting */
  ackm_data->is_ack_eliciting = 1;
 
- /* TODO(QUIC): ADD CODE to send |seq_num| to the ch manager */
+ /* TODO(QUIC): Post MVP ADD CODE to send |seq_num| to the ch manager */
  return 1;
 }
 

ssl/quic/quic_wire.c

@@ -746,6 +746,7 @@ int ossl_quic_wire_decode_frame_new_conn_id(PACKET *pkt,
  if (!expect_frame_header(pkt, OSSL_QUIC_FRAME_TYPE_NEW_CONN_ID)
  || !PACKET_get_quic_vlint(pkt, &f->seq_num)
  || !PACKET_get_quic_vlint(pkt, &f->retire_prior_to)
+ || f->seq_num < f->retire_prior_to
  || !PACKET_get_1(pkt, &len)
  || len > QUIC_MAX_CONN_ID_LEN)
  return 0;